Digital Theses Archive


Tesi etd-02242020-143313

Type of thesis
Functional Sensory Feedback for Upper Limb Prostheses
Scientific disciplinary sector
Istituto di Biorobotica
Istituto di Biorobotica - BIOROBOTICS
  • arm
  • hand
  • nerve stimulation
  • prosthesis
  • prosthetics
  • sensorimotor control
  • sensory feedback
  • upper limb
Exam session start date
Tactile sensory information from the fingertips is essential for efficient use of the hand. Users of upper limb prostheses are deprived of this feedback, rendering even advanced prosthetic hands mere assistive devices at best, and heavy cosmetic prostheses at worst. The lack of hand prostheses providing feedback is owed to the fact that, despite decades of research, it is still unclear how tactile information is best provided to the prosthesis user.<br><br>Perhaps the most significant finding of research on non-invasive feedback was that the crucial discrete discharges of rapidly adapting cutaneous receptors could be substituted by short bursts of vibrotactile stimulation. Other investigators have focused on providing invasive feedback that is perceived in the location of the prosthesis, i.e., somatotopically-matched. However, eliciting reliable natural sensations through direct nerve stimulation has so far proven difficult. Importantly, the majority of research has not been able to prove a functional benefit of artificial sensory feedback in addition to the incidental feedback that prostheses already provide (e.g., visual and auditory cues). Accordingly, there still remains much to discover and assess before truly functional feedback can be provided to prosthesis users.<br><br>My work has thus explored some of the manifold ways of providing feedback to advance our understanding of which information is relevant for prosthesis users and which are the most meaningful ways of providing it. In my studies, I could show that slip feedback is useful and best delivered discretely. Furthermore, my results showed that discrete tactile feedback can be effectively combined with continuous force feedback when provided non-invasively. This hybrid of discrete and continuous stimulation combines discrete feedback that is proven to be effective with the continuous sensation that is desired by prosthesis users. First tests in amputees using direct, i.e., invasive nerve stimulation to deliver this hybrid feedback somatotopically-matched were, however, not conclusive. This thesis will provide a detailed description of my reasoning, my specific research endeavours, as well as their outcomes and projections.<br><br>Future studies will attempt to continue shedding light on the practical usefulness of this novel combination of discrete and continuous feedback in the hope that it will prove functionally relevant not only when being provided non-invasively but also through direct nerve stimulation.